Mobile devices such as smart phones and tablet personal computers (PCs) have been remarkably developed subsequent to standing devices such as personal computers (PCs) and televisions (TVs). Standing devices and mobile devices have been separately developed in respective fields but the differences between the fields have blurred along with the recent boom of digital convergence.
In addition, due to the development and change in environments of such digital devices, user expectation has become high and, thus, there are gradual needs for various high-specification services or application resources.
Generally, a conventional digital TV or the like provides a picture in picture (PIP) function. However, the PIP can be used only in the case of a plurality of tuners for a broadcast service, and since a display window for PIP is configured by previously punching a hole in an on screen display (OSD), movement and so on of the window are difficult. In addition, the PIP service is limited to a broadcast service of a digital device and, thus, it is difficult to apply the PIP service to an application and so on.